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AD7793 Production
The AD7792/AD7793 are low power, low noise, complete analog front ends for high precision measurement applications. The AD7792/AD7793 contain a low noise...
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AD7793 on Analog.com

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daisy chain

		
	
				

			

									
					    Lippy
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Feb 11, 2026 
				
			
			
		
    
		
		                    	    
    
        	    
    Thread Summary
    
                The user seeks to read multiple PT1000 sensors using the AD7793 in a daisy chain configuration but finds that the AD7793 does not support this. The final answer recommends the AD7124-8, which supports multiple RTD sensors, and suggests using the CN-0383 reference design. The user clarifies the need to avoid multiple CS signals and proposes a workaround using a helper circuit and a second CS (CS_CFG) signal to enable daisy chaining.
                        	    
    
                
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    Category: Hardware
    
    		        		            		    
    Product Number:  AD7793  
    
    		        		    		    
    
		    		    
		    			
    
			    
    Hi folks!

    I intend to read multiple PT1000 sensors. Initially I wanted to use AD7793 in daisy chain operation (with one single CS), but after carefully reading digital interface description, I am pretty sure, AD7793 SPI interface does not support daisy chaining. FOr different reasons, I wanto to avoid multiple CS signals.

    Are there any recommendations, maybe another ADC chip?


    thanks in advance.
    Matthias
    
			
    
			
									
		                             
                        

    
    
                                            
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Feb 13, 2026 4:53 AM
            
            
						
			            		
      
		
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      Hi  ,
      

      I will contact the product owner and get back to you soon.
      

      Thanks,
      Francis
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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      •  Analog Employees  
      •  Super User  
      
            
						
                            
            
            				
            
                on Feb 24, 2026 2:02 AM
            
            
						
			            		
      
		
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      Hi  ,
      

      You may want to consider the AD7124-8 Datasheet and Product Info | Analog Devices for your application. It does not support daisy chaining but is able to support multiple RTD sensors to directly interfaced the ADC. We also have a reference design that you may use as a reference in designing your system. CN-0383 (Rev.D)
      

      Hope this helps.
      

      Regards,
      

      JC
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      

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                on Feb 25, 2026 6:54 AM
            
            
						
			            		
        
		
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        Hi!

        Thanks for responding. I will use the provided doc to design the analogue stage.


        Some background. I want to create some monitoring devices for (my) home automation. I intend to monitor fill levels of heating oil and rain water storages and probable some more like water grid pressure, temperature and so on. So at different spots, I want to install a display (cpu unit) and attach as much input stages (adc devices) as needed. Each stage allowing one fil sensor (TL136) and on PT1000 to monitor one storage.

        (I will also provide a M-Bus slave connection to remotely readout this data. But this is not related to this topic)


        Unfortunately, The AD7124 is no option as the "problem" is not the number of sensors (alone). My concept will has a cpu device and multpile (1..X) adc devices stacked together as needed. In the software, each device will be pictured by an own instance of a software class. This is why I want to avoid manually adressing like I2C. So SPI daisy chaining would work best. Due to the mentioned issue, I already thought about some kind of helper-circuit to make be able to daisy chain them. 

        My intension is to use a signal to determine, if another adc device is attached. If not, the SPI loop (MOSI/MISO) will automatically be closed:

         

        And to "addess" only one AD7793, I intend to use a second CS (CS_CFG) signal. This allows me to daisy chain the 74HC595 serial-in-parallel-out shift registers to provide enable signals for only one adc device. When I then use CF_ADC, I can normally talk to the AD7793 as if this ic would be the only one in the SPI loop.

         




        Thanks & Have a good day
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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